1. Technical Field
This invention relates to a drafting apparatus and method for textile fibers. The apparatus and method has particular application for the thinning out of a bundle of staple fibers as is commonly required for the spinning process of yarn. The apparatus and method also serves to even out and to mix fibers by distributing the individual fibers from one cross section of a fiber bundle over a substantial length of a collection surface and can be used for the blending and drawing process of staple fibers.
2. Background Art
Conventional three (3) or four (4) cylinder drafting systems are very effective in thinning out a sliver or roving in order to have this fiber bundle twisted into a spun yarn. However this prior art of drafting results in an increase of the unevenness in the fiber mass. This unevenness also weakens the yarn strand and for this reason, the applied twist in the yarn strand has to be increased. This higher twist has several disadvantages. The higher twist results in lower production. It also compresses the yarn more, resulting in a smaller volume and a harsher yarn.
Prior art of drafting the fiber bundle also lack an effective mixing of the individual fibers, which is especially important with fiber conglomerates of different characteristics, as for example with a fiber blend of cotton and polyester.
The invention described below provides an effective means to even out irregularities in the fiber bundle during the drafting process. It also blends the individual fibers intrinsically, even with dissimilar properties such as different friction coefficient, stiffness, cross section, fiber length et cetera.